用c#修改图片曝光度的方法

Question

我想编一个图片编辑器 ，用c# 怎样实现曝光度大小的调节呢

Answer 1

*******************************请参阅下面两个例子的代码**********************************************下面的代码是将彩色图像变为单色图像的例子。GetPixel(i, j)是用来获得(i, j)位置处的颜色，它包括红绿蓝三色。看下例就明白了private void ToolStripMenuItemGrayR_Click(object sender, EventArgs e)
        {
            Bitmap b = new Bitmap(pictureBox1 .Image );//把图片框1中的图片给一个bitmap类型
            Bitmap b1 = new Bitmap(pictureBox1.Image);
            Color c = new Color();
            //Graphics g1 = pictureBox1.CreateGraphics();//容器设为图片框1
            for (int i = 0; i < pictureBox1.Image.Width ; i++)
                for (int j = 0; j < pictureBox1.Image.Height; j++)
                {
                    c = b1.GetPixel(i, j);
                    Color c1 = Color.FromArgb(c.B, c.B, c.B);//用FromArgb方法由颜色分量值创建Color结构
                    b1.SetPixel(i, j, c1);
                    //pictureBox2.Image = b1;
                    //pictureBox2.Refresh();
                }
            pictureBox2.Image = b1;
            pictureBox2.Refresh();        }再下面这一例，可以得到图片中各个物体的轮廓 private void ToolStripMenuItemOutline_Click(object sender, EventArgs e)
        {
            Color c1 = new Color();    //     Represents an ARGB (alpha, red, green, blue) color.
            Color c2 = new Color();
            Color c3 = new Color();
            Color c4 = new Color();
            int rr, gg, bb, r1, r2, r3, r4, fxr, fyr, i, j;
            int g1, g2, g3, g4, fxg, fyg, b1, b2, b3, b4, fxb, fyb;
            Bitmap box1 = new Bitmap(pictureBox1.Image);//把图片框中的图片给一个bitmap类型//     Encapsulates a GDI+ bitmap, which consists of the pixel data for a graphics
            //     image and its attributes.
            for (i = 0; i < pictureBox1.Image.Width -1 ; i++)
            {
                for (j = 0; j < pictureBox1.Image.Height - 1; j++)
                {
                    c1 = box1.GetPixel(i, j); //   GetPixel(i, j)  Gets the color of the specified pixel in this System.Drawing.Bitmap.
                    c2 = box1.GetPixel(i + 1, j + 1);
                    c3 = box1.GetPixel(i + 1, j);
                    c4 = box1.GetPixel(i, j + 1);
                    r1 = c1.R;
                    r2 = c2.R;
                    r3 = c3.R;
                    r4 = c4.R;
                    fxr = r1 - r2;
                    fyr = r3 - r4;
                    rr = Math.Abs(fxr) + Math.Abs(fyr) ;        //  Math.Abs(fyr)   Returns the absolute value of a 32-bit signed integer.
                    if (rr < 0) rr = 0;
                    if (rr > 255) rr = 255;
                    g1 = c1.G;
                    g2 = c2.G;
                    g3 = c3.G;
                    g4 = c4.G;
                    fxg = g1 - g2;
                    fyg = g3 - g4;
                    gg = Math.Abs(fxg) + Math.Abs(fyg) ;
                    if (gg < 0) gg = 0;
                    if (gg > 255) gg = 255;
                    b1 = c1.B;
                    b2 = c2.B;
                    b3 = c3.B;
                    b4 = c4.B;
                    fxb = b1 - b2;
                    fyb = b3 - b4;
                    bb = Math.Abs(fxb) + Math.Abs(fyb) ;
                    if (bb < 0) bb = 0;
                    if (bb > 255) bb = 255;
                    Color cc = Color.FromArgb(rr, gg, bb);//用FromArgb由颜色分量值创建Color结构
                    //Color cc = Color.FromArgb(rr, rr, rr);//用FromArgb由颜色分量值创建Color结构.获得单色图像
                    //    Color.FromArgb(rr, gg, bb)  Creates a System.Drawing.Color structure from the specified 8-bit color values
                    //     (red, green, and blue). The alpha value is implicitly 255 (fully opaque).
                    //     Although this method allows a 32-bit value to be passed for each color component,
                    //     the value of each component is limited to 8 bits.
                    box1.SetPixel(i, j, cc);        //  box1.SetPixel(i, j, cc)   Sets the color of the specified pixel in this System.Drawing.Bitmap.
                    pictureBox2.Image = box1;
                    label2.Text = Convert.ToString(cc .B );
                }
                pictureBox2.Refresh();//刷新
                pictureBox2.Image = box1;
            }